Various types of fuels may be stored in remote, portable, or transportable tanks to facilitate point of use refueling. Examples of such applications include, without limitation, construction and agriculture. These fuels may include, for example, diesel, gasoline, and kerosene. Often, these types of tanks are not permanent installations, but rather, are meant to be moveable. With these tanks exists a need to seal the tank, while permitting quick and easy fluid removal and replacement. Further, to account for pressure changes that result from a change in fuel volume within the tank, a need further exists to vent the tank.
As will be appreciated by those of ordinary skill in the art, the volume of fuel within a tank can fluctuate over time due to a number of factors, including, for example, fuel being syphoned off (e.g., used to fuel a device), evaporation of the fuel, as well thermal expansion, which may be due to ambient temperature changes. That is, changes in temperature can cause the fuel to expand or contract, thus changing its volume. It is therefore advantageous to counter pressure changes using, for example, a vented fill cap.
Vented fill caps serve two general purposes: (1) to seal the tank to prevent contaminant ingression and evaporative fuel loss; and (2) to provide pressure equalization between the interior of the tank and the atmosphere (i.e., the air/gas external to the tank). Failure to provide pressure equalization between the interior of the tank and the atmosphere when internal tank pressure increases and/or when a vacuum is created can result in destruction of the tank (e.g., due to excess pressure or vacuum). Thus, what is needed is an improved vented fill cap that seals the tank, while permitting for pressure equalization.